The invention relates to an electrical switchgear apparatus of the kind described in the document EP A 0,222,645, for instance a circuit breaker comprising at least one pair of contacts at least one of which is movable and can take with respect to the other a closed position corresponding to mechanical and electrical contact and an open position, this circuit breaker being of the type equipped with a loading mechanism equipped with an energy storage means and with an opening mechanism. The loading mechanism comprises a spring called the closing spring able to move from a loaded state to a released state, and a latch called the closing latch able to lock the closing spring in its loaded state. The closing spring is associated to the movable contact in such a way that release of the closing spring moves the movable contact to its closed position. The loading and closing mechanism comprises in addition a drive mechanism whose drive means, for example an oscillating handle, drives a free-wheel mechanism designed to move the closing spring to its loaded state. The opening mechanism comprises a spring called the opening spring able to move from a loaded state to a released state and from the released state to the loaded state, and a latch called the opening latch able to lock the opening spring in its loaded state. The opening spring is associated to the movable contact in such a way that release of the opening spring moves the movable contact to an open position and that movement of the movable contact to its closed position results in loading of the opening spring.
Such a circuit breaker may be in different states, in particular a closed state, an unloaded open state, and a loaded open state. In the loaded and unloaded open states, the opening latch may be either in the unlatched position, which is generally a rest position in which the latch is flexibly returned, or in the latched position. The latch may in fact be solicited continuously to the latter position, for example by a trip device activating it due to an electrical fault persisting on the line, or by an opening push-button itself latched by an external latch to enable an operation to be carried out on the switchgear apparatus.
The circuit breaker must, however, in practice only be reclosed if three conditions are met: the loading mechanism must be loaded, the switching bar must be in the open position, and the opening latch must be in its latched position. These three conditions being conjunctively met defines a state of the circuit breaker called "ready to close". The 1989 Merlin Gerin low-voltage distribution catalogue references a circuit breaker of Masterpact brand-name presenting an indicator of this ready to close state of the switchgear apparatus. The internal operation of this state of the technique device is represented in FIGS. 1 to 3. The loading mechanism 10 of the circuit breaker 12 comprises an energy storage means with a spring 14 cooperating with a transmission lever 16. The lever 16 is mounted pivoting around a fixed spindle 18 and comprises a roller 20 interfering with a loading cam 22 mounted on a shaft 24. The shaft 24 supports a secondary indexing cam 26 of the state of the circuit breaker 12, interfering with a finger 28 of an indicator 30 pivoting around a fixed spindle 32. The indicator 30 comprises a wall 34 in the form of a cylinder sector, visible through a window 36 of the control panel 38 of the front face of the switchgear apparatus. The indicator 30 can take two positions: one, represented in FIGS. 2 and 3, representative of the not loaded state of the loading mechanism 10 and the other, represented in FIG. 1, representative of the loaded state. In the loaded state of the loading mechanism, i.e. when the spring 14 is stretched to the maximum, in FIG. 1, the finger 28 falls into a notch 40 of the indexing cam 26 and the indicator 30 pivots to a position such that a symbol of the loaded state of the circuit breaker appears in the window 36. When the mechanism is not loaded, the finger 28 interferes with the cylindrical periphery 42 of the cam 26 so that a different part of the wail 34 bearing a corresponding symbol appears in the window. The indicator 30 moreover comprises an arm 44 acting on a slide rack 46 in such a way that the slide rack 46 is pushed to the left in the figures, so long as the circuit breaker is not in its loaded state. Moreover, the circuit breaker has an opening indicator 48 visible in FIG. 3 and fitted on a spindle 50 extending that of the loading indicator 30, in a plane parallel to that of FIG. 1. The opening indicator 48 is biased to an angular position, not represented, in which it lets a symbol of the open state of the circuit breaker appear through a window 52 of the control panel 38. The indicator 48 comprises in addition a finger 54 which interferes with a cam 56 borne by the switching bar 58 when the latter reaches its closed position, so as to make the indicator 48 pivot, which indicator is in the position represented in FIG. 3, in which it lets a symbol of the closed state of the circuit breaker appear through the window 52. In this position, an arm 60 securedly affixed to the indicator interferes with the slide rack 46 in such a way that the slide rack 46 is pushed to the left in the figures so long as the circuit breaker is not in its open state. The opening mechanism of the circuit breaker 12 comprises in addition an opening latch 64 able to take a latched position, represented in FIG. 2, in which it prevents the switching bar 58 from moving from its closed position to its open position, and an unlatched position, represented in FIGS. 1 and 3, in which it allows this movement. The opening latch 64 has an arm 66 acting on the slide rack 46 and pushing the latter to the left in FIG. 2, so long as the latch is in the unlatched position. The slide rack 46 is biased flexibly to the right in the figures, but it can only reach the position of FIG. 1 when all of the three conditions of the "ready to close" state are met with. In this position, the indicator slide rack 46 activates an electrical contact, not represented, which activates a lighted indicator on the control panel 38. Furthermore, it forms in this position, and in this position only, a kinematic link between a closing push-button 68 and a closing latch 70 designed to release the loading cam 22, so that any closing order by the push-button 68 is inoperative so long as the apparatus is not in its ready to close state. This device presents the drawback of not comprising a mechanical indicator, i.e. a purely mechanical device visible by the operator and indicating by its position or its state the "ready to close" state of the apparatus.
To solve this problem, it was proposed in the document EP-A-0,721,647 to provide a mechanical indicator specific of the ready to close state of the apparatus, taking information from a movable part one position of which is specific of the ready to close state. This solution is relatively cumbersome to implement due to the numerous specific parts it involves and to its size. Furthermore, it provides the human operator with superabundant information which does not always prove practical.